abbreviation of "World War I," a major four-year war fought primarily in Europe between the Allies, including France, Great Britain, and the United States, and the Central Powers, including Germany and Austria-Hungary, that ended in 1918 with the collapse of the Central Powers; Great War.

abbreviation of "World War II," the major war of 1939-45, fought between Germany, Italy, and Japan on one side, and Great Britain, the United States, and the Soviet Union on the other. It ended with the collapse of Germany and the surrender of Japan.